1. Field of the Invention
The invention is directed to a pump hose for a peristaltic pump, having its suction-side end and its pressure-side end provided with a bushing integrally connected thereto and being adapted for suspending attachment to the pump by use of holding members.
2. Description of Related Art
In medical applications, peristaltic pumps or hose pumps are used as infusion pumps. Such pumps are used for sterile conveyance of larger quantities of infusion liquid. The exchangeable pump hose is a low-cost disposable product distributed in sterile form with the infeed and discharge hoses of an infusion conduit mounted thereon, and is to be inserted into the pump by the user and then be disposed after use. However, for obtaining continuous conveying accuracy, the pump hose has to fulfill high demands regarding squeezability, elasticity, wear resistance and accuracy to size in longitudinal and transverse directions. The conveying volume depends on the dimensions of the cross section of the pump hose and the restoring ability of the hose. The used material must be physiologically unobjectionable, i.e. inert. It must be precluded that the material is affected by environmental influences such as temperature, atmospheric moisture, light and desinfectants.
Normally, pump hoses for peristaltic pumps are produced from highly elastic materials, e.g. silicone, with high accuracy to size. By use of separate special intermediate pieces, e.g. according to DE-GM 84 06 203, the ends of the infeed and discharge hoses of the infusion conduits have been connected to the pump hose ex factory, and the user inserts the pump hose into a channel of the peristaltic pump and fastens the intermediate pieces to holding devices of the pump housing for fixing the pump hose in its correct position. The pump hose extends between an abutment and pump sliders performing strokes against the hose and compressing it peristaltically. Since one end of the infusion conduit is connected to an infusion liquid container or the like and the other end of the infusion conduit leads to the patient, it is essential upon insertion of the pump hose into the peristaltic pump that the flow direction is correct, i.e. that the infusion container side is located on the suction side of the pump and the patient side is located on the pressure side. Up to now, the correctness of this allocation cannot be easily checked because the bushings mounted to the intermediate pieces look substantially the same and also the intermediate pieces do not allow quick conclusions regarding their respective association to the upper or lower holding devices on the channel of the pump housing.
The continued development in medical science leads to ever increasing demands to the maintenance of certain limit values in infusion technology. At the same time, the large variety of apparatuses and the high working stress of the operating staff have made it still more urgent to provide for simple identification and easy handling. Since maloperation can ultimately put the patient at risk, well-defined fixation of the pump hose has become a matter of safety in medical technology. Using the above intermediate pieces by which the bushings of the pump hose are mounted to the infeed and discharge hoses and which have to be fastened to the pump housing themselves, suffers from the disadvantage that the hose diameter and the hose length--due to tension or upsetting--and the position of the pump hose in the pump are dependent on the respective mounting process so that the conveying or infusion rate cannot be maintained at the required position but varies from one pump hose to another with a relatively large range of tolerances.
A pump hose with integrally formed bushings is disclosed in U.S. Pat. No. 5,088,522. In its undeformed state, this pump hose consists of two arcuate portions so that the hose volume has the cross sectional shape of a biconvex lens. The bushings themselves are formed as circular cylinders. By this cross-sectional shape of the pump hose, the force needed for occlusive closure of the hose by the pump sliders of the peristaltic pump is reduced. The connecting regions of the two arcuate hose wall portions have webs outwardly projecting therefrom, the thickness of said webs substantially corresponding to the sum of the thickness dimensions of the two arcuate portions. These webs serve for decreasing wear and tear of the material by taking up part of the occlusion force acting on the hose from the outside. When setting the force to be exerted on the hose, tolerances of the infusion pump are eliminated.
In a peristaltic pump disclosed in EP 0 024 431, the pump element is formed of two sheets being in face-to-face welding abutment with each other except for a central longitudinal portion. Said longitudinal portion forms a pump chamber having its underside provided with a plurality of cup-shaped flexible structures whose volume is changed by pistons for obtaining the pumping effect. The two axial ends of the longitudinal portion have an inlet hose and an outlet hose connected thereto. On a longitudinal edge of the sheet-shaped pump element, notably in the region of the ends of the pump element, there are formed a longitudinal hole and a circular hole which, when the pump element is laid onto an abutment face on the pump housing, allow passage of circular cylindrical pins projecting from the abutment face. Cooperation of the circular hole with one of the pins is intended to define the correct orientation of the pump element. Such a "push button" is of no use in a pump hose having bushings arranged at its end sides because in such a pump hose it is imperative that the hose be fixed in suspended manner without its conveying volume being affected by changes of size.